As software has developed, manufacturers have provided tablet personal computers offering graphic input functionality. Tablet personal computers offer several advantages, such as powerful calculation ability, broad screens, and particularly intuitive graphic input devices similar to those found in personal digital assistants, all of which can improve users' operation habits, provide more convenience and make personal computers more available for various circumstances.
Generally, a tablet personal computer not only provides a typing input device but also provides a graphic input device. A typical graphic input device comprises a digitizer, such as a touch panel. A user can input signals to the operating system of the tablet personal computer by touching the digitizer via a stylus or fingers. A typical typing input device is used for inputting signals to the operating system of the tablet personal computer by pressing the built-in keys adjacent to the screen of the tablet personal computer. The built-in keys also comprise virtual buttons set on the touch panel, which can be touched to input signals into the operating system of the tablet personal computer.
FIG. 1 is a block diagram illustrating the signal inputting process of a tablet personal computer in accordance with the prior art. Typically, a graphic input device (such as a touch panel or a digitizer 101) and a typing input device (such as a button 103) of a tablet personal computer are respectively controlled by embedded controllers (EC) 105 and EC 107. When the digitizer 101 is touched by a stylus (not shown), a signal is generated and transmitted into the operating system 109 of the tablet personal computer through a RS232 serial communication interface or a USB interface, wherein the EC 105 controls the signal transmitting process. Similarly, when a button 103 is pressed, a signal is generated and transmitted to the operating system 109 of the tablet personal computer, wherein the EC 107 controls the signal transmitting process.
When a user is operating the graphic input device, the button 103 may be touched unintentionally, causing the EC 107 to transmit an undesired signal to the operating system 109 of the tablet personal computer to disrupt the operating system 109.
To resolve this problem, a manual switch is provided to control the EC 107 to ignore signals generated by the button 103 while the graphic input device is being operated.
However, the provision of the switch makes the signal graphic inputting process more complicated and inconvenient.